What is Balsa Wood?

The balsa wood tree, botanically called ochroma lagopus, is a fast growing plant found in Central and South America. Balsa wood trees grow best under the conditions found in rainforests, preferably in mountainous terrain between rivers. Balsa wood is one of the lightest varieties of wood available and can be carved easily with standard woodworking tools and bent into a number of shapes without sacrificing strength. Balsa wood trees propagate much like dandelions; seeds are attached to soft tufts and carried off by the wind. If the seed lands in an area without direct sunlight, such as the dark canopy of the deep forest, it cannot grow. A few seeds may land in a sunlit patch or field and germinate.

Balsa wood trees grow rapidly during their first five years, providing some shade to other plants with their oversized leaves. The ideal balsa wood tree for harvesting is between six and ten years old. After ten years, the inner core of the tree begins to rot and the outer layers become useless. A balsa wood tree is naturally fortified by water stored in large cells. Raw balsa wood has a high moisture content so it must be dried in a kiln for at least two weeks before it can be used commercially. The drying process creates an ultralight wood which is usually cut into sheets or round dowels. Balsa wood does have a grain; some balsa wood is cut across the grain, which makes it suitable for carving but not for weight-bearing struts. Balsa can be found weighing as little as 4 lb per cubic ft up to 24 lb or more per cubic ft (65 to 360 kg/m3). Commercially available balsa for models will weigh between 6 and 18 lb per cubic ft (95 to 285 kg/m3).

Eight to twelve pound balsa (120 to 192 kg/m3) is most plentiful and is considered medium or average weight. Light grade balsa is nominally 6 to 8 lb per cubic ft (95 to 135 kg/m3).